1. Field of the Invention
The present invention relates to a pipette exchange apparatus for use in a device for automatically culturing a biotissue or a cell.
2. Description of the Prior Art
In every field of medical science, biology, pharmacy, agriculture and the like, a technique of culturing biotissues and cells is an inevitable fundamental experimental technique for carrying out research on the cell level. Sub-culture of biotissues and cells, however, is technically difficult, and no stable cultured strain can be obtained.
Recently, a technique of gas culture in an incubator, i.e., a culture technique in particular gas atmosphere, has been promoted, and as a result, special cells such as the liver, nervous system, hypophysis cerebri and the like, which have hitherto been difficult to be cultured, can be cultured now.
The present measure for culturing such cells will be described as follows. At first, in order to carry out subculture, a predetermined number of cells is diluted by a culture solution, poured into a culture container such as a Petri dish and cultured in an incubator kept in a predetermined atmosphere as it is maintained still. After a lapse of a predetermined time, a predetermined culture container is taken out of the incubator for the purpose of checking the culture condition and the degree of cell proliferation is examined by a microscope. When it is confirmed that the cells aimed at are proliferated by filling up the container, the container is replaced to a clean bench under asepsis condition, the culture solution in the culture container is sucked by a pippette and thrown away, the cells remained in the container is washed by injecting a buffer solution, and the buffer solution used for such washing is again sucked and thrown away. Then, in order to separate the cells embedded on the bottom surface of the culture container and proliferated from the culture container, an enzyme such as trypsin is injected therein, left as it is for several minutes and thrown away. After leaving for several minutes, a culture solution is again injected. This culture solution has the action of stopping activity of the trypsin. After injecting and stirring, the culture solution is moved to a centrifugal tube and centrifuged. A supernatant liquid of the thus centrifuged culture solution is absorbed and thrown away. A culture solution is injected and stirred to refloat the cells, a refloated cell-floating solution is injected into a culture container by every estimation and a culture solution is divided and injected for obtaining a predetermined concentration. The culture container after completion of the dilute dividing and injection operation is taken out of the clean bench, moved into the incubator kept in a predetermined atmosphere, stood still, and culture is again started.
However, the above explained measure has the following detects.
One of the defects is that in order to check the proliferation condition of a tissue or a cell by a microscope, it is often necessary to take the culture container from the incubator outside into the open air. Therefore, the culture condition is rapidly changed by taking it into the open air from a predetermined environmental condition such as gas atmosphere, temperature, humidity, etc., and as a result, the tissue or cell to be cultured is delicately changed. Because of the exposure to the open air, there is further caused contamination due to saprophyte. Thus, there is the susceptibility to a direct effect such as an influence caused by a change of the environmental condition and an invasion of saprophyte.
Another defect is that, since a technician manually carries out a sub-culture operation of the aforementioned cell separation-collection-dilution-division based on the result of observation by a microscope, his operation has a direct influence upon the cultured tissue or cell. That is, the prior culture operation cannot obtain standardized culture under a certain condition. The cultured tissue or cell depends upon the technician's experience and skill. Accordingly, it means that standardization and unification of the culture technique itself are very difficult. Even in case of carrying out a research of the same theme, therefore, various conclusions are derived according to each researcher.
A technician having enough culture technique should be trained for a number of years, and such technicians are absolutely in short supply. So, a researcher cannot be absorbed in his original study but must be spared his energy for the culture technique which is a subordinate problem.
From the above, there has been developed an automatic culture device aiming at prevention of air contamination caused by a conventional measure, removal of any influence of manual operation and automatic culture of standardized tissues or cells by standardizing and unifying each operation.
In this automatic culture device, a dividing injector is placed for moving the aforementioned proliferated cell from the culture container to the centrifugal separator, throwing the supernatant solution after centrifuge, injecting the culture solution into the centrifugal separator, dividing the refloated cell into a new culture container and the like, and the injector is placed in a culture room kept in a certain atmosphere, and the above operation is carried out in such culture atmosphere. In these operations, for example, a pipette used for throwing away the supernatant liquid after centrifuge is contaminated by the supernatant liquid, so that it is not preferable to use such pipette for injecting the next culture solution and dividing the cell into the new culture container.